The invention relates to an apparatus for testing the state of the optical system of an endoscope, comprising a first supporting device for the endoscope, a test pattern and a second supporting device for the test pattern.
Such an apparatus is known from U.S. Pat. No. 5,820,547.
An endoscope is particularly used in minimal-invasive surgery as a viewing instrument in order to be able to control from the outside an operation performed through a small incision in the body.
Endoscopes are, however, not only used in medical applications, but also in technical applications, e.g. for observing cavities in machines, combustion chambers of engines and the like, which cannot be observed with the naked eye.
The main element of an endoscope is its optical system. The optical system of an endoscope consists of rod lenses or glass fibers and objective lenses and eyepiece lenses. An endoscope can, additionally, comprise a light conducting system for illuminating the area to be observed. There is a plurality of endoscope types, which differ from each other by their endoscope-specific basic data. Such endoscope-specific basic data are e.g. the angle of view or the viewing direction and the field of view angle of an endoscope. Furthermore, endoscopes can also differ by the magnification ratio of the optical imaging and, moreover, by their geometrical dimensions.
With reference to the viewing direction of the endoscope, there are endoscopes with a straight forward viewing direction, i.e. the viewing direction of the endoscope forms an angle of 0xc2x0 with the longitudinal axis of the shaft of the endoscope. There are also endoscopes with an oblique view optic, i.e. the viewing direction of the endoscope runs then in an oblique fashion with respect to the longitudinal axis of the shaft in a predetermined angle.
The optical system of an endoscope can be impaired by external influences in the course of time, so that the quality of the image transmission by the optical system is deteriorated and/or deviations of the nominal values of the basic data occur. Medical endoscopes in particular are sterilized after each use, the endoscopes being exposed to hot vapor under high pressure in an autoclave to this end. But also mechanical influences like impacts onto the shaft, e.g. when the endoscope falls down, may impair the optical system of the endoscope.
It is, thus, necessary to revise and/or to repair the endoscope after some time. There is the problem herewith that, if the reparation is improperly performed by not authorized workshops, the initial original state and/or quality standard of the optic is not achieved. For the manufacturer of the endoscope, there is, thus, the need, due to the requirements of customer service, to be able to check the state of the endoscopes with reference to their basic data in a quick and simple manner at least with reference to quality within acceptable tolerances. This includes, besides the qualitative check of the viewing direction and of the field of view angle, e.g. a qualitative estimation of the sharpness and/or of the contrast of the image transmission in the image center and/or in the border region of the image and, if necessary, a check of the state of the light conducting system, should the endoscope be equipped with such a system.
In U.S. Pat. No. 5,820,547 mentioned above, a portable apparatus that is simple in design for testing the state of the optical system of an endoscope is described, which comprises a supporting device for the endoscope to be examined and a test pattern and a supporting device for the test pattern. The supporting device for the endoscope consists of a cylindrical adapter comprising an axial central through bore, into which the distal end portion of the endoscope is inserted. For endoscopes with an oblique view optic, two lateral through bores that run obliquely to the longitudinal axis of the tube are provided, into which these endoscopes can be suitably inserted. The test pattern is fixed at a supporting device, which is firmly connected with the supporting device for the endoscope. The test pattern consists of an arrangement of line patterns of different line thickness, of a line grid and of an arrangement of concentric circles.
While this known apparatus is very simple in design, it has, however, the disadvantage not to be universally adapted to a plurality of different optical systems of endoscopes. For example, the distance between the test pattern and the distal end of the endoscope is firmly predetermined. As the distance between the test pattern and the distal end of the endoscope is firmly predetermined, in an observation of the test pattern through the endoscope, in dependency of the field of view angle, circle sectors of different sizes are seen, respectively, what makes the evaluation of the test more difficult for a user who is not trained technically. Moreover, only endoscope optics with three different viewing directions that are firmly predetermined on the adapter can be tested. The accuracy of the test, apart from that, is low. A check of the function of the light conducting system of the endoscope exceeding this test is not possible.
On the other hand, from U.S. Pat. No. 5,841,525, an apparatus for testing the state of the optical system of an endoscope is known, which is, however, very expensive and which requires periphery equipment like image processing equipment and a computer station for the evaluation of the test. This apparatus is, thus, not transportable and is not suited for performing a quick test in a different location at a customer""s.
Further, U.S. Pat. No. 4,613,232 discloses a portable measuring device for testing optical systems of an endoscope consisting of a base plate, a rail with a longitudinally extending V groove for receiving a portion of the endoscope being mounted to extend parallel to the plate on a carriage movable at right angles to the groove. The device includes a vertical shaft mounted on the plate and terminating at one end in a conical point, and the shaft carries at least one extension arm which is mounted to pivot in a plane parallel to the base plate. Each arm adjustably supports a measuring disk which can have its height above the plate changed or its distance from the shaft changed. This known apparatus comprises a measuring disk having known scales and the like, whereby it is possible to exactly measure the angular field, the sight line, the diameter of the exit pupil, the subject field illumination, the depth of field, the focusing range, the visual lens magnification, the distortion and the resolution of the optical system of the endoscope being tested.
The invention has, thus, the object to improve an apparatus of the type mentioned at the outset in such a way that it allows a quick assessment of the quality and a check of the basic data and/or the image quality without time-intensive training of the user.
According to the invention, the object underlying the present invention is achieved with an apparatus for testing the state of an optical system of an endoscope having a viewing direction and a field of view angle, said apparatus comprising a first supporting device for said endoscope, a test pattern and a second supporting device for said test pattern, wherein said test pattern comprises a pattern, which allows a common check of an actual viewing direction and of an actual field of view angle of said optical system of said endoscope within tolerance values of a nominal value of said viewing direction and a nominal value of said field of view angle.
With this embodiment of the test pattern, the viewing direction and the field of view angle can be checked together in a quick and simple way, i.e. it is possible to judge in a quick and simple manner whether the endoscope tested is defective or in an acceptable state within the tolerances predetermined by the pattern. With the apparatus according to the invention, tests of endoscopes can be carried out by service employees without previous time-intensive training in a location at a customer""s.
In a preferred embodiment, the pattern of the test pattern comprises a circular reference line as nominal value for the ideal viewing direction and for the ideal field of view angle, and a tolerance field, which is formed by rings that are arranged on both sides of the reference line.
By this embodiment of the test pattern, a check of the state of the viewing direction and of the field of view angle that is particularly simple to perform is allowed, because the testing person merely needs to orientate himself or herself by means of simple geometrical patterns. The reference line corresponds to the outer edge of the field of view to be observed through an ideal endoscope.
In another preferred embodiment, the test pattern comprises a pattern, which allows a check of the image quality.
By this embodiment, in addition to the common check of the viewing direction and of the field of view angle, at the same time a check of the image quality, i.e. the image sharpness by means of a geometrical pattern is made possible. The pattern for checking the image quality can be formed by an arrangement of line patterns of different line thickness on the test pattern, these line patterns being such arranged on the test pattern that the line patterns in the image center and at the image edge of the region of the test pattern observable by an ideal endoscope can be recognized. Preferably, the pattern comprises a periodical repetition of line patterns of different line thickness, so that these line patterns are observable at the image edge of the region of the test disk observable by an ideal endoscope can be recognized over the entire circumference of the image edge.
In another preferred embodiment, the first supporting device and the second supporting device can be positioned relative to each other, so that the relative position of the test pattern is endoscope-specifically adjustable with respect to the endoscope.
Instead of connecting the supporting device for the endoscope and the supporting device for the test pattern immovably to each other, as in the known apparatus of the prior art, the apparatus according to the invention provides to configure the supporting device for the endoscope and the supporting device for the test pattern positionable relative to each other, i.e. in a movable fashion, so that the relative position of the test pattern to the endoscope in dependency on endoscope-specific data of the endoscope to be tested is definedly adjustable. This offers, advantageously, the possibility of positioning the test pattern for all existing types of optical systems of endoscopes of the most different basic data such that always the same section of the test pattern is seen through the endoscope optic, so that deviations from the nominal state can be realized more easily. While the first supporting device and/or the second supporting device are positioned corresponding to the endoscope-specific data, e.g. by means of positional values that can be taken from a table, a procedure which is simple to learn even without time-intensive training, also the check of the basic data of different endoscopes is possible in a quick and easy manner because always the same features of the test pattern independent of the endoscope tested have to be evaluated. The apparatus according to the invention is, moreover, universally applicable for all existing endoscopes with the most different endoscope optics and can also be extended onto endoscope optics which, up to now, do not exist.
In a preferred embodiment, the distance between the test pattern and the endoscope is adjustable.
It is herein advantageous that, with the apparatus, a plurality of different endoscopes can be tested, which differ from each other by their predetermined field of view angle.
In another preferred embodiment, an angle between a normal line of the test pattern and the longitudinal direction of the endoscope can be adjusted.
It is herein advantageous that, with the apparatus according to the invention, a plurality of the most different endoscopes can be tested, which differ from each other by their predetermined viewing direction.
In another preferred embodiment, positional values for positioning the test pattern and/or the endoscope are allocated to endoscope-specific data of the endoscope.
The use of positional values for inserting the endoscope into the apparatus and/or for positioning the test pattern further facilitates the handling of the apparatus. The positional values can e.g. be listed in a table and can be registered as positional marks in the apparatus.
In a further preferred embodiment, the first supporting device comprises at least one first support displaceable on a first rail in longitudinal direction, the rail extending in longitudinal direction of the endoscope.
This measure has the advantage that also the endoscopes to be tested themselves can be positioned in a suitable way in the apparatus. In that way, the apparatus according to the invention is also suitable for testing endoscopes having shafts of different lengths. In particular in connection with the measure mentioned before, in which the angle between the normal line of the test pattern and the longitudinal direction of the endoscope is data-specifically adjustable, it is advantageously ensured by this measure that, even with differently long endoscope shafts, the normal line of the test pattern is always congruent with the optical axis of the viewing direction of the endoscope because the tip of the endoscope is always located at a defined point in the apparatus.
It is further preferred if the support supports the endoscope in a predetermined rotary position with respect to a longitudinal axis of the endoscope for fixing the endoscope.
In particular for endoscopes with oblique viewing optic, this measure ensures that the viewing direction of the endoscope is, if possible, vertical on the test pattern.
In another preferred embodiment, the first rail comprises a first positioning scale and the first support comprises a first scale rider that is axially displaceable on the first rail for axial positioning of the support.
By the embodiment already mentioned before of the first supporting device with a rail and a support displaceable thereon, a continuously adjustable positioning of the endoscope is achieved, whereby the apparatus is suitable for all existing lengths of endoscopes. By means of the positioning scale provided on the rail and the scale rider that is displaceable on the rail, now a positioning of the respective endoscope can be carried out by means of tabled values in a way that is particularly simple to handle. For example, for all existing different endoscopes, positional values in the form of numbers or letter-number-combinations can be listed in a table, wherein the positioning scale comprises these positioning values as markers. The scale rider can, further, comprise a vernier or the like for a fine adjustment of the position of the endoscope.
In a corresponding preferred embodiment, the second supporting device that supports the test pattern comprises a second support that is displaceable on a second rail in longitudinal direction of the rail.
By means of this support movable in longitudinal direction, now, the distance between the test pattern and the distal end of the endoscope can be adjusted in a simple to handle manner, and the distance, again, is continuously adjustable to any different endoscopes.
Also herein, it is preferred if the second rail comprises a second positioning scale and the second support comprises a scale rider that is displaceable on the second rail for axial positioning the second support on the second rail.
In that way, the distance between the test pattern and the distal end of the endoscope can be exactly adjusted by means of tabled values, by adjusting the axial position of the support of the test pattern to the tabled value accordingly.
In another preferred embodiment, the first rail and the second rail are connected with each other via a rotary joint.
Compared to the apparatus known in the prior art that comprises three bores for inserting the endoscope shafts for the test of endoscopes of different viewing directions, the embodiment of the connection of the two rails with a rotary joint according to the invention has the advantage that the possibility of a continuous angle adjustment between the two supporting devices is given, whereby endoscopes with any viewing direction can be tested.
It is here further preferred if a third positioning scale for adjusting the angle between the first rail and the second rail is circumferentially arranged at the rotary joint.
Like for the positioning scales of the first supporting device and the second supporting device, it is here also advantageous that the defined angle adjustment between the test pattern and the endoscope that is required for the respective endoscope can be done by means of tabled values and, thus, is particularly simple in handling.
It is further preferred if a set disk is arranged at the rotary joint, the set disk comprising the third positioning scale, and which is rotatable relative to the first rail and relative to the second rail.
By this measure, the entire circumference of a set disk can advantageously be equipped with a positioning scale, wherein, by turning the set disk, first of all, a basic adjustment and then, by pivoting the second rail relative to the set disk, the angle between the first and the second rail can be adjusted.
In another preferred embodiment, the test pattern comprises a pattern that allows a check of the viewing direction, of the field of view angle and/or of the image quality.
In this embodiment of the test pattern, the essential basic data of an endoscope and/or its deviations beyond predetermined tolerances can be quickly and easily determined.
In another preferred embodiment, the apparatus further comprises an illumination light test device for testing a light conducting system of the endoscope to be tested.
By means of this measure, the flexibility of the apparatus according to the invention is further increased, as also an illumination light test of the light conducting system of the endoscope can be carried out.
In order to be able to carry out the illumination light test by means of construction that is simple in design and simple in handling, the illumination light test device comprises preferably a photodetector that is movable into a position in front of the light emerging side of the endoscope and that is connected with a displaying device for displaying the light intensity.
In order to further facilitate the illumination light test and to make same easily evaluable even for staff that is not technically trained, the displaying device comprises a calibration device, e.g. a potentiometer, by means of which the displaying device is adjustable to a reference value.
With the same light source that is used for the illumination light test of the endoscope, first, the photodetector can be irradiated directly, i.e. without that the light is conducted through the endoscope, and the displaying device can be calibrated to a predetermined reference value. After that, with the same light source, the light is directed onto the photodetector through the light conducting system of the endoscope, and the person carrying out the test can then read the actual value of the light intensity and compare same with a nominal value in a table.
In order to further facilitate the reference measuring, the illumination light test device comprises preferably a light cable connection for connecting a light cable, wherein the photo detector can be brought into a position in which it is arranged adjacently to the light cable connection.
In another preferred embodiment, the photo detector is fixed at a third supporting device, which comprises a support pivotably arranged at an arm that is connected with the second rail.
By means of this measure, the illumination light test device is advantageously integrated in the second supporting device for the test pattern, and the photodetector can advantageously simply be moved in front of the distal end of the endoscope to be tested and in front of the light cable connection for the reference measuring. By fixing the support at the second rail that is pivoted relative to the first rail corresponding to the viewing direction of the endoscope, also the light of the endoscope orthogonally hits the photodetector.
Further features and advantages can be taken from the following description and the enclosed drawings.
It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention.